Compositions comprising IMPDH inhibitors and uses thereof for treating HCV infection

ABSTRACT

The present invention relates to optimal compositions useful in treating HCV infections in humans. These compositions comprise alpha-interferon or pegylated alpha-interferon and an IMPDH inhibitor selected from VX-148 or VX-944, wherein the IMPDH inhibitor is present in an amount such that a ratio of Cavg/Cmin is between 1 to 10, wherein:
         Cavg is average plasma concentration produced by said IMPDH inhibitor in said human; and   Cmin is estimated trough concentration produced by said IMPDH inhibitor in said human.       

     The present invention also relates to methods of producing and using the optimal compositions to treat HCV infections in humans.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to optimal compositions useful in treatingHCV infections in humans. These compositions comprise alpha-interferonand an IMPDH inhibitor, wherein the IMPDH inhibitor is present in anamount such that a ratio of Cavg/Cmin is between 1 to 10, wherein:

-   -   Cavg is average plasma concentration produced by said IMPDH        inhibitor in said human; and

Cmin is estimated trough concentration produced by said IMPDH inhibitorin said human.

The present invention relates to optimal compositions useful in treatingHCV infections in humans. These compositions comprise alpha-interferonand an IMPDH inhibitor, wherein the IMPDH inhibitor is present in anamount such that a ratio of Cavg/Cmin is between 1 to 10, wherein:

-   -   Cavg is average plasma concentration produced by said IMPDH        inhibitor in said human; and    -   Cmin is estimated trough concentration produced by said IMPDH        inhibitor in said human.

The present invention also relates to methods of producing and using theoptimal compositions to treat HCV infections in humans.

BACKGROUND OF THE INVENTION

Hepatitis C virus (“HCV”) infection is a common cause of viralhepatitis. It is estimated that 3% of the world's population is infectedwith HCV. (Clarke, B. E., Balliere's Clinical Gastroenterology, 14, No.2, pp. 293-305 (2000). Until recently, alpha-interferon was the firsttherapy with proven benefit for treating HCV infection. Depletion ofcellular guanine nucleotide reservoirs via inhibition of theNAD+-dependent enzyme, inosine monophosphate dehydrogenase (“IMPDH”),which is the rate-limiting enzyme in the de novo nucleotidebiosynthesis, has been identified as an attractive target for anti-HCVtherapy. See, VX-497, Drugs of the Future, 25(8), pp. 809-814 (2000).Known inhibitors of IMPDH include Ribavirin, VX-497, mycophenolatemofetil (CELLCEPT®), tiazofurin and mizoribine. Recently, a combinationtherapy, using alpha-interferon and Ribavirin™, has shown greaterefficacy in treating HCV infection than a monotherapy using eitherentity. However, the combination therapy is not problem free. Alphainterferon is known to cause side effects such as high fevers,headaches, nausea and depression. Ribavirin tends to increase these sideeffects, and also cause haemolytic anaemia. Hepatologists are reluctantto reduce the dosage of Ribavirin below 800 mg/day (see, Foster, G. R.and Thomas, H. C., Balliere's Clinical Gastroenterology, 14(2), pp.255-264 (2000). The minimum effective dose of Ribavirin is not yetknown.

Thus, there is a need for a therapy that takes advantage of the synergyand/or additivity observed between alpha-interferon and an IMPDHinhibitor in the combination therapy, but preferably without thedrawbacks associated with the individual components of the combinationtherapy.

Thus, there is a need for an optimal composition for treating HCVinfection in a human, comprising alpha-interferon and an IMPDHinhibitor.

There is also a need for a method for treating HCV infection in a humancomprising the step of administering to said human an optimalcomposition comprising alpha-interferon and an IMPDH inhibitor.

There is also a need for a method for evaluating the suitability of acomposition comprising an IMPDH inhibitor and alpha-interferon foroptimally treating HCV infection in a human.

There is also a need for a method of producing an optimal compositionfor treating HCV infection in a human, wherein said optimal compositioncomprises alpha-interferon and an IMPDH inhibitor.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an optimalcomposition for treating HCV infection in a human, comprisingalpha-interferon and an IMPDH inhibitor, wherein said IMPDH inhibitor ispresent in said composition in an amount such that a ratio of Cavg/Cminis between 1 to 10;

-   -   wherein:    -   Cavg is average plasma concentration produced by said IMPDH        inhibitor in said human; and    -   Cmin is estimated trough concentration produced by said IMPDH        inhibitor in said human.

It is another object of the present invention to provide a method fortreating HCV infection in a human comprising the step of administeringto said human an optimal composition comprising alpha-interferon and anIMPDH inhibitor, wherein said optimal composition contains said IMPDHinhibitor in an amount such that a ratio of Cavg/Cmin is between 1 to10;

-   -   wherein Cavg and Cmin are as described above.

It is yet another object of the present invention to provide a methodfor evaluating the suitability of a composition comprising an IMPDHinhibitor and alpha-interferon for treating HCV infection in a human,said method comprising the steps of:

-   -   a. administering to said human said composition comprising said        IMPDH inhibitor and said alpha-interferon;    -   b. determining average plasma concentration produced by said        IMPDH inhibitor in said human (“Cavg”);    -   c. determining trough concentration produced by said IMPDH        inhibitor in said human (“Cmin”);    -   d. calculating a ratio of Cavg/Cmin;    -   e. deeming said composition to be suitable for treating HCV        infection if said ratio is between 1 to 10.

It is yet another object of the present invention to provide a method ofproducing an optimal composition for treating HCV infection in a human,wherein said optimal composition comprises alpha-interferon and anoptimal amount of an IMPDH inhibitor, said method comprising the stepsof:

-   -   a. administering to said human a first composition comprising a        first amount of said IMPDH inhibitor and said alpha-interferon;    -   b. determining average plasma concentration produced by said        first amount of said IMPDH inhibitor in said human (“Cavg”);    -   c. determining trough concentration produced by said first        amount of said IMPDH inhibitor in said human (“Cmin”);    -   d. calculating a ratio of said Cavg to said Cmin;    -   e. modifying said first amount of said IMPDH inhibitor in said        first composition to produce said optimal composition wherein        said ratio is between 1 to 10.

DETAILED DESCRIPTION OF THE INVENTION

According to one embodiment, the present invention provides an optimalcomposition for treating HCV infection in a human. An optimalcomposition according to the present invention comprisesalpha-interferon or a derivative thereof, an IMPDH inhibitor and apharmaceutical carrier, wherein said IMPDH inhibitor is present in saidcomposition in an amount such that a ratio of Cavg/Cmin is between 1 to10;

-   -   wherein:    -   Cavg is average steady-state plasma concentration produced by        said IMPDH inhibitor in said human; and    -   Cmin is estimated trough concentration produced by said IMPDH        inhibitor in said human.

Cavg is equal to AUC/T, wherein AUC is the area under the plasmaconcentration-time curve during a dosing interval of time T. Cavg andCmin are readily determined by known techniques in the art. See, e.g.,Gibaldi, M. and Perrier, D., Pharmacokinetics, 2^(nd) Ed., MarcelDekker, Inc. (1982); Khakoo, S. et al., Br. J. Clin. Pharmacol.46, pp.563-570 (1998); Glue, P., Sem. Liver. Dis. 19, pp. 17-24 (1999).

The term “IMPDH inhibitor” as used in the present invention refers toany compound having the ability to measurably inhibit the activity ofIMPDH. IMPDH inhibitors well known in the art include mycophenolic acid,ribavirin, VX-497, VX-148 or VX-944.

Thus, according to another embodiment, the present invention provides anoptimal composition comprising alpha-interferon or a derivative thereof,an IMPDH inhibitor and a pharmaceutical carrier, wherein said IMPDHinhibitor is present in said composition in an amount such that a ratioof Cavg/Cmin is between 1 to 10; and wherein said inhibitor is selectedfrom mycophenolic acid, ribavirin, VX-497, VX-148 or VX-944.

According to another embodiment, the present invention provides anoptimal composition comprising alpha-interferon or a derivative thereof,an IMPDH inhibitor and a pharmaceutical carrier, wherein said IMPDHinhibitor is present in said composition in an amount such that a ratioof Cavg/Cmin is between 1 to 10; and wherein said inhibitor is selectedfrom ribavirin or VX-497.

According to an alternate embodiment, the IMPDH inhibitor is ribavirin.

According to an alternate embodiment, the IMPDH inhibitor ismycophenolic acid.

According to yet another embodiment, the IMPDH inhibitor is VX-497.

IMPDH inhibitors are known to have immunosuppressive andanti-proliferative activity by depletion of guanine nucleotide pools.Due to this anti-proliferative activity, IMPDH inhibitors such asmycophenolic acid and mizoribine are used to prevent acute graftrejection in renal and cardiac transplant patients.

However, IMPDH inhibitors are also known to have anti-viral activity.Thus, in any anti-viral therapy using IMPDH inhibitors, it is desirableto use concentrations wherein the anti-viral activity of the IMPDHinhibitor is maximized over the anti-proliferative activity. The presentinvention provides a band of IMPDH inhibitor concentrations, wherein thelower end of the band is defined by the ratio Cavg/Cmin being 1, and theupper end of the band is defined by that ratio being 10.

Without wishing to be bound by theory, applicants believe that thefollowing analysis underpins the anti-viral activity of the IMPDHinhibitor:

Each IMPDH inhibitor has different IC50 values for itsanti-proliferative activity (“IC50_(ap)”) and its anti-viral activity(“IC50_(av)”). The ratio of IC50_(av)/IC50_(ap) is the Conversion Factor(“CV”), useful in converting an anti-proliferative response into ananti-viral response.

The anti-proliferative quotient (“APQ”) for a given IMPDH inhibitor,i.e., the relative-fold above IC50_(ap) value of Cavg is defined as:APQ=Cavg/IC50_(ap)

The APQ can be converted to the corresponding anti-viral quotient(“AAQ”) for a given IMPDH inhibitor using the Conversion Factordescribed above:

$\begin{matrix}{{AAQ} = {{APQ}/{CV}}} \\{= {\left( {{Cavg}/{{IC}50}_{ap}} \right)/\left( {{{IC}50}_{av}/{{IC}50}_{ap}} \right)}} \\{= {{Cavg}/{{IC}50}_{av}}}\end{matrix}$

The anti-viral activity is affected, in part, by the troughconcentration of the IMPDH inhibitor (Cmin). Thus, the ratioCmin/IC50_(av) is defined as the Forgiveness Quotient (“FQ”) andrepresents the relative-fold above IC50_(av) value of Cmin.

Thus, for each IMPDH inhibitor, there exists an Anti-viral Index (“AI”),defined as:

$\begin{matrix}{{AI} = {{AAQ}/{FQ}}} \\{= {\left( {{Cavg}/{{IC}50}_{av}} \right)/\left( {{Cmin}/{{IC}50}_{av}} \right)}} \\{= {{Cavg}/{Cmin}}}\end{matrix}$

Applicants believe that when AI, i.e., the ratio of Cavg/Cmin, isgreater than 10, this implies that either Cavg is too high or Cmin istoo low. In either event, the anti-proliferative response will tend tomask the anti-viral response, resulting in a sub-optimal level ofobserved anti-viral activity.

According to one embodiment, the ratio of Cavg/Cmin is between 3-8.

According to another embodiment, the ratio of Cavg/Cmin is between 5-8.

According to another embodiment, the ratio of Cavg/Cmin is between 1-5.

According to another embodiment, the ratio of Cavg/Cmin is between 4-6.

According to another embodiment, the present invention provides a methodfor treating HCV infection in a human comprising the step ofadministering to said human an optimal composition, wherein said optimalcomposition is as described above.

According to another embodiment, a single dosage of the optimalcomposition is employed in the method of treating HCV infectionaccording to the present invention.

According to another embodiment, a multiple dosage regimen is employedfor administering the optimal composition in the method of treating HCVinfection according to the present invention.

According to another embodiment, the present invention provides a methodfor evaluating the suitability of a composition comprising an IMPDHinhibitor and alpha-interferon or a derivative thereof for treating HCVinfection in a human, said method comprising the steps of:

-   -   a. administering to said human said composition comprising said        IMPDH inhibitor and said alpha-interferon;    -   b. determining average plasma concentration produced by said        IMPDH inhibitor in said human (“Cavg”);    -   c. determining trough concentration produced by said IMPDH        inhibitor in said human (“Cmin”);    -   d. calculating a ratio of Cavg/Cmin;    -   e. deeming said composition to be suitable for treating HCV        infection if said ratio is between 1 to 10.

According to another embodiment, the present invention provides a methodof producing an optimal composition for treating HCV infection in ahuman, wherein said optimal composition is as defined above. The methodcomprises the steps of:

-   -   a. administering to said human a first composition comprising a        first amount of said IMPDH inhibitor and said alpha-interferon;    -   b. determining average plasma concentration produced by said        first amount of said IMPDH inhibitor in said human (“Cavg”);    -   c. determining trough concentration produced by said first        amount of said IMPDH inhibitor in said human (“Cmin”);    -   d. calculating a ratio of said Cavg to said Cmin;    -   e. modifying said first amount of said IMPDH inhibitor in said        first composition to produce said optimal composition wherein        said ratio is between 1 to 10.

According to another embodiment of the present invention, the ratio ofCavg/Cmin is between 1-8.

According to another embodiment of the present invention, the ratio ofCavg/Cmin is between 3-8.

According to another embodiment of the present invention, the ratio ofCavg/Cmin is between 5-8.

According to yet another embodiment, the present invention provides acomposition for treating HCV infection in a human, comprisingalpha-interferon or pegylated alpha interferon and an IMPDH inhibitorselected from VX-148 or VX-944, wherein said IMPDH inhibitor is presentin said composition in an amount such that a ratio of Cavg/Cmin isbetween 1 to 10;

-   -   wherein:    -   Cavg is average plasma concentration produced by said IMPDH        inhibitor in said human; and    -   Cmin is estimated trough concentration produced by said IMPDH        inhibitor in said human.

The structures of VX-944 and VX-148 are:

According to yet another embodiment, the present invention provides amethod for treating HCV infection in a human comprising the step ofadministering to said human a composition comprising alpha-interferon orpegylated alpha-interferon and an IMPDH inhibitor selected from VX-148or VX-944, wherein said optimal composition comprises said IMPDHinhibitor in an amount such that a ratio of Cavg/Cmin is between 1 to10;

-   -   wherein:    -   Cavg is average plasma concentration produced by said IMPDH        inhibitor in said human; and    -   Cmin is estimated trough concentration produced by said IMPDH        inhibitor in said human.

According to one embodiment, the method for treating HCV infection in ahuman comprises alpha-interferon or pegylated interferon and VX-148.

According to another embodiment, the method for treating HCV infectionin a human comprises alpha-interferon or pegylated interferon and VX-148and the ratio of Cavg/Cmin is between 1 to 8.

According to another embodiment, the method for treating HCV infectionin a human comprises alpha-interferon or pegylated interferon and VX-148and the ratio of Cavg/Cmin is between 3 to 8.

According to another embodiment, the method for treating HCV infectionin a human comprises alpha-interferon or pegylated interferon and VX-148and the ratio of Cavg/Cmin is between 5 to 8.

According to another embodiment, the method for treating HCV infectionin a human comprises alpha-interferon or pegylated interferon andVX-944.

According to another embodiment, the method for treating HCV infectionin a human comprises alpha-interferon or pegylated interferon and VX-944and the ratio of Cavg/Cmin is between 1 to 8.

According to another embodiment, the method for treating HCV infectionin a human comprises alpha-interferon or pegylated interferon and VX-944and the ratio of Cavg/Cmin is between 3 to 8.

According to another embodiment, the method for treating HCV infectionin a human comprises alpha-interferon or pegylated interferon and VX-944and the ratio of Cavg/Cmin is between 5 to 8.

According to yet another embodiment, the present invention provides amethod of producing an optimal composition for treating HCV infection ina human, said method comprising the steps of:

-   -   a. administering to said human a first composition comprising a        first amount of VX-148 or VX-944 and alpha-interferon or        pegylated alpha-interferon;    -   b. determining average plasma concentration produced by said        first amount of VX-148 or VX-944 in said human (“Cavg”);    -   c. determining trough concentration produced by said first        amount of VX-148 or VX-944 in said human (“Cmin”);    -   d. calculating a ratio of said Cavg to said Cmin;    -   e. modifying said first amount of VX-148 or VX-944 in said first        composition to a second amount of said VX-148 or said VX-944        such that said ratio is between 1 to 10; and    -   f. combining said second amount of said VX-148 or said VX-944        with said alpha-interferon or pegylated alpha-interferon to        produce said composition.

According to one embodiment, the method of producing an optimalcomposition for treating HCV infection in a human comprises, for each ofsteps a. through f., alpha-interferon or pegylated interferon andVX-148.

According to another embodiment, the method of producing an optimalcomposition for treating HCV infection in a human comprises, for each ofsteps a. through f., alpha-interferon or pegylated interferon and VX-148and the ratio of Cavg/Cmin is between 1 to 8.

According to another embodiment, the method of producing an optimalcomposition for treating HCV infection in a human comprises, for each ofsteps a. through f., alpha-interferon or pegylated interferon and VX-148and the ratio of Cavg/Cmin is between 3 to 8.

According to another embodiment, the method of producing an optimalcomposition for treating HCV infection in a human comprises, for each ofsteps a. through f., alpha-interferon or pegylated interferon and VX-148and the ratio of Cavg/Cmin is between 5 to 8.

According to yet another embodiment, the method of producing an optimalcomposition for treating HCV infection in a human comprises, for each ofsteps a. through f., alpha-interferon or pegylated interferon andVX-944.

According to another embodiment, the method of producing an optimalcomposition for treating HCV infection in a human comprises, for each ofsteps a. through f., alpha-interferon or pegylated interferon and VX-944and the ratio of Cavg/Cmin is between 1 to 8.

According to another embodiment, the method of producing an optimalcomposition for treating HCV infection in a human comprises, for each ofsteps a. through f., alpha-interferon or pegylated interferon and VX-944and the ratio of Cavg/Cmin is between 3 to 8.

According to another embodiment, the method of producing an optimalcomposition for treating HCV infection in a human comprises, for each ofsteps a. through f., alpha-interferon or pegylated interferon and VX-944and the ratio of Cavg/Cmin is between 5 to 8.

Pharmaceutically acceptable carriers that may be used in the optimalcompositions of the present invention include, but are not limited to,ion exchangers, alumina, aluminum stearate, lecithin, serum proteins,such as human serum albumin, buffer substances such as phosphates,glycine, sorbic acid, potassium sorbate, partial glyceride mixtures ofsaturated vegetable fatty acids, water, salts or electrolytes, such asprotamine sulfate, disodium hydrogen phosphate, potassium hydrogenphosphate, sodium chloride, zinc salts, colloidal silica, magnesiumtrisilicate, polyvinyl pyrrolidone, cellulose-based substances,polyethylene glycol, sodium carboxymethylcellulose, polyacrylates,waxes, polyethylene-polyoxypropylene-block polymers, polyethylene glycoland wool fat.

Such optimal pharmaceutical compositions of the present invention may beadministered orally, parenterally, by inhalation spray, rectally,nasally, buccally, vaginally or via an implanted reservoir. The term“parenteral” as used herein includes subcutaneous, intravenous,intramuscular, intra-articular, intra-synovial, intrasternal,intrathecal, intrahepatic, intralesional and intracranial injection orinfusion techniques. Preferably, the compositions are administeredorally, subcutaneously or intravenously.

Sterile injectable forms of the compositions of this invention may beaqueous or oleaginous suspension. These suspensions may be formulatedaccording to techniques known in the art using suitable dispersing orwetting agents and suspending agents. The sterile injectable preparationmay also be a sterile injectable solution or suspension in a non-toxicparenterally acceptable diluent or solvent, for example as a solution in1,3-butanediol. Among the acceptable vehicles and solvents that may beemployed are water, Ringer's solution and isotonic sodium chloridesolution. In addition, sterile, fixed oils are conventionally employedas a solvent or suspending medium. For this purpose, any bland fixed oilmay be employed including synthetic mono- or di-glycerides. Fatty acids,such as oleic acid and its glyceride derivatives are useful in thepreparation of injectables, as are natural pharmaceutically-acceptableoils, such as olive oil or castor oil, especially in theirpolyoxyethylated versions. These oil solutions or suspensions may alsocontain a long-chain alcohol diluent or dispersant, such ascarboxymethyl cellulose or similar dispersing agents which are commonlyused in the formulation of pharmaceutically acceptable dosage formsincluding emulsions and suspensions. Other commonly used surfactants,such as Tweens, Spans and other emulsifying agents or bioavailabilityenhancers which are commonly used in the manufacture of pharmaceuticallyacceptable solid, liquid, or other dosage forms may also be used for thepurposes of formulation.

The optimal compositions of this invention may be orally administered inany orally acceptable dosage form including, but not limited to,capsules, tablets, aqueous suspensions or solutions. In the case oftablets for oral use, carriers that are commonly used include lactoseand corn starch. Lubricating agents, such as magnesium stearate, arealso typically added. For oral administration in a capsule form, usefuldiluents include lactose and dried cornstarch. When aqueous suspensionsare required for oral use, the active ingredient is combined withemulsifying and suspending agents. If desired, certain sweetening,flavoring or coloring agents may also be added.

Alternatively, the optimal compositions of this invention may beadministered in the form of suppositories for rectal administration.These may be prepared by mixing the agent with a suitable non-irritatingexcipient which is solid at room temperature but liquid at rectaltemperature and therefore will melt in the rectum to release the drug.Such materials include cocoa butter, beeswax and polyethylene glycols.

The optimal compositions of this invention may also be administered bynasal aerosol or inhalation. Such optimal compositions are preparedaccording to techniques well known in the art of pharmaceuticalformulation and may be prepared as solutions in saline, employing benzylalcohol or other suitable preservatives, absorption promoters to enhancebioavailability, fluorocarbons, and/or other conventional solubilizingor dispersing agents.

Most preferred are optimal compositions formulated for oraladministration.

In order that this invention be more fully understood, the followingexamples are set forth. These examples are for the purpose ofillustration only, and are not to be construed as limiting the scope ofthe invention in any way.

VX-148 and VX-944 may be prepared according to the methods described inissued U.S. Pat. No. 6,498,178, the entirety of which is hereinincorporated by reference.

EXAMPLE 1

The combination therapy of interferon alpha (IFN) and ribavirin (RBV)adopted and evaluated the administration of maximum tolerated doses ofboth drugs (3 million units (MU) IFN three times a week (tiw)+600 mg RBVtwice daily (BID)). Since the effects of IFN are indirect, a clearrelationship between plasma concentration and antiviral effects has notbeen established. It is believed that the effects of RBV in thecombination regimen ensure prevention of relapse amongst responders toIFN therapy. The latter hypothesis has been supported by higherproportion of patients having longer-term viral clearance (HCV RNAnegative) following cessation of therapy, which is referred to as thesustained response (SR) rates. McHutchison and Poynard, Sem. Liver Dis.19, 57-65 (1999), have shown that in two major phase III trials, SR ingenotype 1 and non-genotype 1 patients averaged around 30 and 60%,respectively. However, the MTD of ribavirin causes significant hemolyticanemia and various trials have indicated that dropping the ribavirindose by one-half (to 600 mg daily) caused no significant change in SR.See, McHutchison & Poynard, Sem. Liver Dis. 19:57-65 (1999).

As shown in Table 2a below, the FQ for RBV at any of the doses listed iswell below 1 at any of the doses studied, while achieving significantantiviral effects. This surprising result indicates that the combinationof IFN with IMPDH inhibitors requires a low FQ.

Our algorithm predicts that there exists an optimal balance between theantiproliferative activity and the antiviral activity for ribavirin incombination with IFN. For instance, the average trough concentrations ofribavirin are about 3.6- to 19.5-fold above the IC50 for inhibition ofproliferation of peripheral blood lymphocytes (PBLs). Per our algorithmdescribed above, a “conversion factor” of 12.25 needs to be applied tothe APQ to account for antiviral effects as distinct from theantiproliferative effects of ribavirin. Thus the corrected APQ (i.e.AAQ) for ribavirin ranges from 0.3 to 1.6.

The AI for ribavirin ranges between 5 to 8 across the three dosesstudied. Hence, an optimal dose of ribavirin is such that its averageconcentration is near its concentration required for IMPDH inhibition incell proliferation and the trough concentration is such that it allowsfor no greater than 10-fold ratio between APQ and FQ. Thus daily dosesof 200 mg twice daily or 400 mg once daily, up to 600 mg twice dailywould be effective as an IMPDH inhibitor for the inhibition of hepatitisC virus replication in combination with IFN.

TABLE 1 Effects of Interferon alpha 2b (INTRON A ®) and Ribavirin in HCVpatients Dose of IC50ap IC50av Cavg Cmin HCV RNA Ribavirin (ng/mL)(ng/mL)* (ng/ml) (ng/mL) APQ AAQ FQ drop 600 mg 976 11956 19000 225019.5 1.6 0.19 30%^(a), BID 60%^(b) 400 mg 976 11956 7083 1450 7.3 0.60.12 N/A BID 200 mg 976 11956 3542 740 3.6 0.3 0.06 N/A BID *MicromolarIC50 of ribavirin in Table 1 converted to ng/mL using a molecular weightof 244. **Estimated per the single dose kinetics reported by Glue, P,Sem. Liver Dis. 19: 17-24, and using the accumulation factor reported byKhakoo et al. Br. J. Clin. Pharmacol., 46, pp. 563-570 (1998). Cavg iscalculated from AUC(0-t)/dosing interval. ^(†)Data for SR fromMcHutchison and Poynard (1999), see above. ^(a)For genotype 1; ^(b)Fornon-genotype 1. N/A: Not available

EXAMPLE 2

A four week safety and pharmacokinetic study was conducted in naivehepatitis C patients to evaluate the pharmacodynamic effects of two doselevels of VX-497 (100 mg q 8 hrs and 300 mg q 8 hrs) in combination with3 MU of IFN alpha 2b tiw. The evaluation of the antiviral activity (withbaseline HCV RNA as a covariate) of VX-497 showed that 100 mg TIDproduced a higher reduction in viral load than the 300 mg TID doselevel. As seen in Table 2b, a lower FQ for VX-497 with the standard doseof IFN produced a similar or slightly better initial antiviral effect.Given the lower FQ for RBV in table 2 above, once again a surprisingresult of lower FQ giving better antiviral effects is seen.

The AAQ for VX-497's antiviral response is estimated to range between 1and 8. When the AI is calculated, a range from 1.4 to 4.4 are obtainedacross all the doses for the AI. AS per our algorithm, VX-497 doselevels of 50 mg BID up to 100 mg BID are also expected to elicit similaror better antiviral effects in combination with IFN as those seen in theinitial antiviral study at 100 mg TID and 300 mg TID. Thus, an AI of 1-5is considered optimal for VX-497+IFN for inhibition of hepatitis C viralreplication.

TABLE 2 Effects of Interferon alpha 2b (INTRON A ®) and VX-497 in naïveHCV patients Dose of VX- IC50ap IC50av* Cavg** Cmin** % HCV RNA 497(ng/mL) (ng/mL) (ng/ml) (ng/mL) APQ AAQ FQ drop 300 mg 45 140 1107 25024.6 7.93 1.8 50% TID 100 mg 45 140 520 168 11.6 3.74 1.2 53% TID 100 mg45 140 359 262 8 2.6 1.9 N/A BID 50 mg 45 140 266 116 5.9 1.9 0.83 N/ATID 50 mg 45 140 150 107 3.3 1.06 0.76 N/A BID *Micromolar IC50 in Table1 converted to ng/mL using the molecular weight of VX-497 as 452.**Estimated assuming linearity and based upon expected steady-stateconcentrations and Cavg = AUC(0-t)/dosing interval ***From VX-497-003trial in genotype 1 naive patients receiving INTRON-A ® with VX-497 for4 weeks N/A: Not available

EXAMPLE 3

A four-week analysis of the antiviral effects of the combination ofpegylated IFN-2a (PEGASYS®) with the MTD of mycophenolate (as themofetil ester, CELLCEPT® at 1000 mg BID) showed a lower proportion ofpatients achieving significant antiviral effects, when compared to agroup receiving PEGASYS® and RBV. However, when treated for six monthswith PEGASYS® and CELLCEPT®, similar “end of treatment” antiviralefficacy was observed for MMF and PEGASYS® as the combination ofribavirin and PEGASYS®.

Once again, the AAQ for MMF is critical in determining the activity ofMMF in combination with PEGASYS® in hepatitis C patients. It is quiteevident that the AAQ for all three dose levels of mycophenolate are wellbelow 1. It is important to understand that in vitro inhibitoryconcentrations of MMF have not been predictive of in vivo EC50 for MMF.Numerous reasons for this phenomenon include rapid glucuronidation, andenterohepatic recirculation. Hence, a correction for APQ is obtained bydividing average plasma concentration by in vivo IC50.

In the case of mycophenolate, there is clear evidence of in vivo IMPDHinhibition requiring much higher concentrations. Therefore, the FQ iscorrected for the loss of in vitro potency (a factor of 337.5). The AIis obtained by correcting the APQ for the fold change betweenantiproliferative to antiviral IC50 in vitro and an AI is obtained fromthe algorithm described. For mycophenolate, all three dose levels listedproduce a ratio in the range of 1.9 to 2.5. Hence, it is expected thatmycophenolate at doses of 0.5 g to 1 g twice daily in combination withIFN and/or its pharmaceutical dosage forms (such as PEGINTRON® andPEGASYS®), will elicit an antiviral response in hepatitis C patients.

TABLE 3 Effects of Mycophenolate with pegylated IFN-2a (PEGASYS ®) inHCV patients IC50ap % Dose (ng/mL) IC50ap** HCV of in (ng/mL) IC50av*Cavg*** Cmin** RNA MPA vitro in vivo (ng/mL) (ng/mL) (ng/mL) APQ AAQ FQdrop 1000 mg 32 10800 122 3869 2060 0.36 0.095 0.05 31^(a), BID 72^(b)750 mg 32 10800 122 3425 1400 0.32 0.084 0.034 N/A BID 500 mg 32 10800122 3163 1630 0.29 0.076 0.04 N/A BID Micromolar IC₅₀ of mycophenolatein Table 1 converted to ng/mL using a molecular weight of 320.**Estimated from Brunet et al., Transpl Int 2000; 13 (Suppl 1):S301-S305 ***Cavg obtained from median AUC(0-t)/dosing interval fromBrunet et al., Transpl. Int., 13, pp. 301-305 (2000) ^(†)In vivo IMPDHinhibition correction factor estimated as the ratio of in vivo IC50/invitro IC50 for cellular proliferation (i.e. 10800/32 = 337.5) ^(††)Datafrom Nezam Afdel and Steven K. Herrine (presented at DDW, 6/2001)^(a)For non-responders to REBETRON ® with 90% genotype 1 patients^(b)For relapsers on REBETRON ® with 79% genotype 1 patients N/A: Notavailable

1. A composition for treating HCV infection in a human, comprisingalpha-interferon or pegylated alpha interferon and an IMPDH inhibitorselected from VX-148 or VX-944:

wherein said IMPDH inhibitor is present in said composition in an amountsuch that a ratio of Cavg/Cmin is between 1 to 10; wherein: Cavg isaverage plasma concentration produced by said IMPDH inhibitor in saidhuman; and Cmin is estimated trough concentration produced by said IMPDHinhibitor in said human.
 2. The composition according to claim 1,wherein said ratio is between 3-8.
 3. The composition according to claim2, wherein said ratio is between 5-8.
 4. The composition according toclaim 1, wherein said ratio is between 4-6.
 5. The composition accordingto claim 1, wherein said ratio is between 1-5.
 6. A method for treatingHCV infection in a human comprising the step of administering to saidhuman a composition comprising alpha-interferon or pegylatedalpha-interferon and an IMPDH inhibitor selected from VX-148 or VX-944:

wherein said optimal composition comprises said IMPDH inhibitor in anamount such that a ratio of Cavg/Cmin is between 1 to 10; wherein: Cavgis average plasma concentration produced by said IMPDH inhibitor in saidhuman; and Cmin is estimated trough concentration produced by said IMPDHinhibitor in said human.
 7. A method of producing an optimal compositionfor treating HCV infection in a human, said method comprising the stepsof: a. administering to said human a first composition comprising afirst amount of VX-148 or VX-944 and alpha-interferon or pegylatedalpha-interferon; b. determining average plasma concentration producedby said first amount of VX-148 or VX-944 in said human (“Cavg”); c.determining trough concentration produced by said first amount of VX-148or VX-944 in said human (“Cmin”); d. calculating a ratio of said Cavg tosaid Cmin; e. modifying said first amount of VX-148 or VX-944 in saidfirst composition to a second amount of said VX-148 or said VX-944 suchthat said ratio is between 1 to 10; and f. combining said second amountof said VX-148 or said VX-944 with said alpha-interferon or pegylatedalpha-interferon to produce said composition; wherein the formula ofsaid VX-148 and VX-944 are:


8. The method according to any one of claims 6-7, wherein said ratio isbetween 1-8.
 9. The method according to claim 8, wherein said ratio isbetween 3-8.
 10. The method according to claim 9, wherein said ratio isbetween 5-8.
 11. The method according to claim 10, wherein said IMPDHinhibitor is VX-148.
 12. The method according to claim 10, wherein saidIMPDH inhibitor is VX-944.